Error handling for custom values

dfred · **Joined:** Fri Jul 23, 2010 11:49 pm **Posts:** 29

I have an animated mask path on layer 1 and I am trying to handle an "After Effects error" with the following expression in source text:

Code:

try {
x = thisComp.layer(1).mask(1).maskPath.velocity;
}
catch (err) {
x = "error";
}

The error I keep getting is:

Quote:

After Effects error: can't compute derivative to a non-spatial custom value ( 29 :: 57 )

The try/catch statement doesn't seem to work in this case for some reason. Any ideas on how to handle this error?

dfred · **Joined:** Fri Jul 23, 2010 11:49 pm **Posts:** 29

Apparently it's unable to be handled. According to the JavaScript Tools Guide:

Quote:

Messaging error codes
Negative values indicate unrecoverable errors...
-29 Uncaught exception
57 Cannot resolve reference

So, I came up with this ugly solution:

Code:

maskPath = thisComp.layer(1).mask(1).maskPath;
try {
    if (maskPath.numKeys > 0){
        throw ("err1");
    } else {
        x = maskPath.velocity;
    }
}
catch (err) {
    x = "error";
}

I would much rather have a way to read through expressions:

Code:

maskPath.propertyValueType.CUSTOM_VALUE == true

I guess I'll have to do it through scripting for now. So, let me know if anybody has a better solution.

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Error handling for custom values

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